Abstract:

As a critical node connecting spore germination and sporophyte formation， the gametophyte plays a vital role in the reproduction and survival of ferns， serving as the central hub of the fern life cycle. In this study， aseptic culture of Cystopteris chinensis spores was conducted to observe and document the entire process of spore germination and gametophyte development under a light microscope. The results showed that the spores of C. chinensis had an average size of 32.83 μm×27.37 μm， appearing elliptical in polar view and semicircular in equatorial view； the length of the single laesura nearly extended to the equatorial line， the perispore ornamentation was spinose， and additional small verrucous or tuberculate protrusions were present on the spore surface. Spores began to germinate 12 days after sowing， enter the filamentous stage after 15 days， develop into prothalli after 30 days， and differentiate into sex organs after 50 days. The spore germination type was centripetal， and the prothallus development followed the Aspidium-type. The mature prothallus was symmetrically broad and rounded cordate， with an average size of 2.9 mm×1.8 mm； sparse trichomes were present on the margin， dorsal and ventral surfaces of the prothallus. The archegonia and antheridia were borne on separate prothalli， with a ratio of female to male prothalli being approximately 5∶1.The archegonia were composed of four rows of cells， with a height of approximately 75 μm and a diameter of approximately 45 μm； the antheridia were spherical， with a height of approximately 49 μm and a diameter of approximately 44 μm. The archegonia were brown after fertilization. The gametophyte developmental characteristics of C. chinensis resembled those of the bulbifera clade within the genus Cystopteris， suggesting a close genetic relationship.

Key words: fern, Cystopteris chinensis, gametophyte development